HELP!! ballistics chart?!?!?!

[hoosier85]

Its Question time once again. So I would like to create a infield reference card for my rifle. I have the ballistics info for the rounds which are hornady 75gr V max rounds. I found out for the V Max rounds at 200yds its zero, 300yds its -5.8", 400 its -17.6", and finally at 500 its -36.9. I also know that one MOA is an angle which subtends an arc whose length is 1.047 inches at 100 yards. At 100 meters, is subtends an arc whose length is about 1.145 inches. where do I go from here? Everyone tries to explain it online but so far I am confusing my self. If my scope is 1/4" MOA it would take four clicks (the noise it make when I turn my turrent) to have moved my crosshairs an inch at 100 yard, 2 at 200 yards and so on. Sooooooo at 400 yards I know that the drop is down 17.6" so i would have to adjust my turrent 17 times? this does not sound right??
I think my brain needs a breather

[jab89]

Converting your drop numbers into MOA instead of inches of drop may help. If you are using a ballistic calculator to get your numbers most are capable of showing you an moa number. Your 37 inch drop at 500 would be roughly 7 MOA so 28 quarter minute clicks

[BallisticsNut]

100 yard, 2 at 200 yards and so on. Sooooooo at 400 yards I know that the drop is down 17.6" so i would have to adjust my turrent 17 times? this does not sound right??
I think my brain needs a breather

 

As I understand it, your correct.  At 400 yards one MOA (Minute of angle) equals 1.047 x 4 or 4.188".  One "click" equals on quarter MOA.  So, at 400 yards, one click equals 1.047".  To calculate your drop (without windage taken in consideration) of 17.6 is roughly 17 "clicks".   I would also consider windage direction and speed.  This could changes your drop considerably if you have a head wind or cross wind. 

If you have an iPhone, download the Ballistic program by Jonathan Zdziarski.  GREAT program for calculating ballistics while taking in consideration weather, elevations, wind direction etc.

http://ballistic.zdziarski.com

[JimmyHoffa]

Are those numbers that came from a test rifle or from data entered from your rifle/hunting conditions---elev, temp, scope height, muzzle velocity?

[CastleRocker]

Wow!  This is the first time I've ever wanted an I-phone!  That looks like a really useful app.  One would have to do a lot of "proof" type shooting to see how accurate it is though.  Great concept, and I can't imagine the amount of work and research it took to put together.

[hoosier85]

So one cannot really make a reliable drop chart then... if you have to take in drag coefficient, muzzle velocity, target elevation, range wind speed, wind angle, altitude, temp, humidity, and all this other stuff. Why do I hear everyone saying they have a reliable drop chart? There is also a ap for droids, search for ballistics in the market.

[norsepeak]

Yes you can make very accurate drop charts, and 17.6"of drop at 400 yards is 17.6/4=4.4 moa x 4 clicks per moa=18 clicks assuming you clicks are actually.25 moa which can only be proven with a ladder test.

[Bob33]

So one cannot really make a reliable drop chart then... if you have to take in drag coefficient, muzzle velocity, target elevation, range wind speed, wind angle, altitude, temp, humidity, and all this other stuff. Why do I hear everyone saying they have a reliable drop chart? There is also a ap for droids, search for ballistics in the market.

Drag coefficient: yes, you need to know the "ballistic coefficient".  You can easily find it from the bullet manufacturers.
Muzzle velocity: yes, you need to know it.  You can get a close approximation from the ammunition manufacturer for factory ammo, or better yet from a chronograph.
Target elevation: not sure how that differs from "altitude".  If this is referring to the relative angle to the target, that matters but only with extreme angles (30 degrees or more at short to intermediate distances.)
Wind speed: not particularly important for drop in most cases, but important for horizontal movement.  A 10 mph crosswind can blow a bullet one foot or more at 400 yards.
Wind angle: a wind blowing straight at or straight away from you has little effect.
Altitude:  not vastly important until you get to distances past 400 or 500 yards.  Higher altitudes = less air pressure = less bullet resistance = less drop.
Temperature: not vastly important at short to intermediate distances.
Humidity: not vastly important at short to intermediate distances.

Out to 400 or even 500 yards, you are best to get a rough approximation, and then go shoot and see how the bullet actually drops and drifts.  If you plan to shoot at longer distances like 800 yards then yes, these variables can make a significant difference.

[hoosier85]

I think i have it as close as I am going to get it till I go out shooting tomorrow. I am a more hands on guy anyways. If I take something apart or go up and see how it works I can pretty much make you one or fix it. I have been buying rounds left and right so I think I will get her figured out. It seems like I got a little frustrated because some of these guys on other sites make it sound like you have to be jonny sniper to hit something. oh well I guess I will let ya guys know how it goes either way a day out shooting... come on whats better besides a day hunting. Thanks everyone

[Bob33]

You have the right frame of mind.  Go shoot, take good notes, and have fun.

[hoosier85]

Thanks bob

[JimmyHoffa]

Naw, you don't need to be jonny sniper.  Even snipers had to start somewhere.  The reason I asked is I often see ballistics charts and in the past tried to make a range card, but it seems quite a bit of the ballistics charts aren't quite representative of the more common rifles or where they'll be used.  For example, I think most .30-06 rifles are pretty much standard from manufacturers with 22 inch barrels.  Then you look at the rifle used to calculate the chart for the ammo manufacturer and it has a 24 inch barrel.  So your velocity is rough (lower than test).  They do most of the charts at 70 F and sea level.  Also scope height is important for trajectory claculations.  Most of the test rifles are 1.5" above the barrel if I remember correctly.  For my AR (old type with handle) my scope sits about 4.5", which throws me a bit below before the chart zero and quite high beyond their zero point.  I think you can get rough with manufacturer provided data and then tune it in with your own observations.  You can make different range cards for the same ammo, for when you have a significant chane in environmental factors.